A man can swim in still water at a speed of 4km/h. He desires to cross a river flowing at a speed of 3km/h in the shortest time interval. If the width of the river is 3km.Find the time taken to cross the river and the horizontal distance traveled by the man?

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Asked 12/24/2008 8:39:38 AM

Updated 8/17/2023 1:35:24 AM

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Flagged by Here_To_Help_You [10/8/2020 6:42:03 PM]

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Question

Asked 12/24/2008 8:39:38 AM

Updated 8/17/2023 1:35:24 AM

1 Answer/Comment

This conversation has been flagged as incorrect.

Flagged by Here_To_Help_You [10/8/2020 6:42:03 PM]

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To find the shortest time interval for the man to cross the river, he should swim at a direction that is perpendicular to the river's flow. This way, the effective speed across the river is the difference between his swimming speed and the river's flow speed.

Given:

- Man's swimming speed in still water: 4 km/h

- River's flow speed: 3 km/h

- Width of the river: 3 km

1. Time taken to cross the river:

The effective speed across the river is the square root of (4^2 - 3^2) = 5 km/h (using Pythagoras' theorem).

Time = Distance / Speed = 3 km / 5 km/h = 0.6 hours = 36 minutes.

2. Horizontal distance traveled:

The horizontal distance traveled by the man is the same as the width of the river since he swims perpendicular to the river's flow.

Horizontal distance = Width of the river = 3 km.

So, the time taken to cross the river is 36 minutes, and the horizontal distance traveled by the man is 3 km.

Given:

- Man's swimming speed in still water: 4 km/h

- River's flow speed: 3 km/h

- Width of the river: 3 km

1. Time taken to cross the river:

The effective speed across the river is the square root of (4^2 - 3^2) = 5 km/h (using Pythagoras' theorem).

Time = Distance / Speed = 3 km / 5 km/h = 0.6 hours = 36 minutes.

2. Horizontal distance traveled:

The horizontal distance traveled by the man is the same as the width of the river since he swims perpendicular to the river's flow.

Horizontal distance = Width of the river = 3 km.

So, the time taken to cross the river is 36 minutes, and the horizontal distance traveled by the man is 3 km.

Added 8/17/2023 1:35:24 AM

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